Grok 4 vs Step 3.5 Flash
Grok 4 (2025) and Step 3.5 Flash (2026) are frontier-tier reasoning models from xAI and StepFun. Grok 4 ships a 256k-token context window, while Step 3.5 Flash ships a 256k-token context window. On SWE-bench Verified, Grok 4 leads by 2.3 pts. On pricing, Step 3.5 Flash costs $0.10/1M input tokens versus $1.25/1M for the alternative. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Step 3.5 Flash is ~1150% cheaper at $0.10/1M; pay for Grok 4 only for coding workflow support.
Decision scorecard
Local evidence first| Signal | Grok 4 | Step 3.5 Flash |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | reasoning-heavy apps |
| Decision fit | Coding, RAG, and Agents | Coding, Agents, and Long context |
| Context window | 256k | 256k |
| Cheapest output | $2.50/1M tokens | $0.30/1M tokens |
| Provider routes | 4 tracked | 1 tracked |
| Shared benchmarks | SWE-bench Verified leader | 3 shared |
Decision tradeoffs
- Grok 4 holds a shared-benchmark lead on SWE-bench Verified, ahead by 2.3 points.
- Grok 4 has broader tracked provider coverage for fallback and route flexibility.
- Grok 4 uniquely exposes Vision, Multimodal, and JSON / Tool use in local model data.
- Local decision data tags Grok 4 for Coding, RAG, and Agents.
- Step 3.5 Flash holds a shared-benchmark lead on AIME 2025, ahead by 5.6 points.
- Step 3.5 Flash has the lower cheapest tracked output price at $0.30/1M tokens.
- Local decision data tags Step 3.5 Flash for Coding, Agents, and Long context.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Grok 4
$1,625
Cheapest tracked route/tier: xAI Console
Step 3.5 Flash
$155
Cheapest tracked route/tier: OpenRouter
Estimated monthly gap: $1,470. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Step 3.5 Flash is $2.20/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Vision, Multimodal, and JSON / Tool use before moving production traffic.
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Grok 4 is $2.20/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Grok 4 adds Vision, Multimodal, and JSON / Tool use in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-07-09 | 2026-01-29 |
| Context window | 256k | 256k |
| Parameters | — | 196B (11B active) |
| Architecture | Decoder Only | Mixture of Experts |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Weights | Not released | Not released |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | - | - |
Pricing and availability
| Pricing attribute | Grok 4 | Step 3.5 Flash |
|---|---|---|
| Input price | $1.25/1M tokens | $0.10/1M tokens |
| Output price | $2.50/1M tokens | $0.30/1M tokens |
| Providers |
Capabilities
| Capability | Grok 4 | Step 3.5 Flash |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | Yes | Yes |
| JSON / Tool use | Yes | No |
| Structured outputs | Yes | No |
| Code execution | Yes | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | Grok 4 | Step 3.5 Flash |
|---|---|---|
| SWE-bench Verified | 76.7 | 74.4 |
| AIME 2025 | 91.7 | 97.3 |
| LiveCodeBench | 79.0 | 86.4 |
Continue comparing
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Last reviewed: 2026-07-10. Data sourced from public model cards and provider documentation.